Problem with the screen for Medieval 2 PC

I started playing medieval 2 a few days ago and everything works fine except for one thing. The screen isnt full screen like other games ive played. I dont understand why its that way. What i mean is its kinda like when you stretch a page out and there are open areas left out on the left and right side, well thats how it is when i play. Its pretty much that the gameplay is in the center and the left and right sides are a bit open and are in black. I can see everything but its hard to see details because its small. I tried making it widescreen through the options but it doesnt work either. Any advice would be appreciated.